If you’d prefer not to go the UICollectionView route, or don’t need reordering here’s an open source library that allows you to easily enable drag and drop between any UIViews, even UIPopover views called OBDragDrop from Oblong Industries.

As the readme states:

– Drag and drop between any UIViews – Any view can be draggable, and any view can be a drop target – Visuals exists on a UIWindow that sits on top of the app – Various events for different stages of a drag and drop gesture

Included is an example demonstrating the drag and drop functionality between views including popovers.